1. Field of the Invention
This invention lies in the field of methods for making multi-layered reclosable bag making material and to certain bag making material and bags produced therefrom.
2. Prior Art
Containers incorporating fasteners having cooperating pressure-releasable and reclosable interlocking members for container closure means have been made by various techniques. By one technique, the interlocking elements are directly integrally extruded with and as part of plastic sheeting to be subsequently formed into containers. By another technique, the interlocking elements are separately extruded onto a film to which the interlocking elements are heat bonded. By another technique, an adhesive is employed to adhere preformed interlocking elements to a preformed film.
A technique for joining a plastic fastener strip continuously to a film is taught by Takahashi U.S. Pat. No. 4,279,677.
In order to improve (reduce) the gas and vapor transmission, or other barrier characteristics of prior art containers in this field, it would be desirable to utilize multi-layered or laminated superimposed plastic sheets. For example, Uramoto U.S. Pat. No. 3,827,472 teaches a flexible bag structure wherein wall members are comprised of a laminate and wherein the inner wall has an integrally co-extruded set of releasable interlocking elements formed therein in adjacent relationship to the bag mouth. However, because of profile density considerations, particularly in the region of the interlocking elements, it is difficult to co-extrude such wall members at high speed in a commercially practical manner and in commercial quality.
In order to improve (reduce) the gas and vapor transmission, or other barrier characteristics of prior art containers in this field, it would be desirable to utilize multi-layered or laminated superimposed plastic sheets. For example, Uramoto U.S. Pat. No. 3,827,472 teaches a flexible bag structure wherein wall members are comprised of a laminate and wherein the inner wall has an integrally co-extruded set of releasable interlocking elements formed therein in adjacent relationship to the bag mouth. However, because of profile density considerations, particularly in the region of the interlocking elements, it is difficult to co-extrude such wall members at high speed in a commercially practical manner and in commercial quality.
In Herz U.S. Pat. Nos. 4,372,793 and 4,341,575, there is provided technology whereby preformed extruded flexible fastener profiles are secured to plastic film by means of an adhesive, such as a hot melt adhesive, which is applied between, and limited to the width of the strips carrying the profiles and the plastic film at the time of mounting. While this method does permit the attainment of high speed production, the method is not adapted for the preparation of laminate sheets by extrusion or other coating techniques.
The art needs new and improved technology for making laminated reclosable bags and material useful for making such bags.